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Traitement du signal en interferometrie monomode dans le cadre du projet AMBER. Application a l'observation interferometrique de l'environnement > circumstellaire des etoiles jeunes

Abstract : Recent progresses of optical interferometry, in terms of spatial resolution, sensitivity and precision of the measurements, made this technique particularly well suited to study the close environment of young stars which hold the keys of stellar and planet formation. As a matter of fact, the first interferometric observations have unveiled many essential informations on the physical nature of the surrounding structure of these objects. The AMBER instrument, the near infrared three beams recombiner of the Very Large Telescope Interferometer (VLTI), will, by pioneering the era of interferometric imaging with both very high spatial and spectral resolution, allow to move one step forward in the understanding of the physical processes governing these stars. This work is organized around the AMBER instrument. After summarizing the general principles of optical interferometry in presence of atmospheric turbulence, I show why introducing waveguides in the recombination scheme allows, by taking advantage of their properties of spatial filtering, to increase the precision and the robustness of the measurements. From this theoretical basis, I then develop the AMBER data reduction procedures, with stressing the innovative specificities of the interferometric signal processing. The algorithms have been tested and validated though simulations and then applied to the observation of the Herbig Be star MWC 297 in medium spectral resolution. This young star presents a strong emission line due to the atomic transition of the hydrogen $\mathrm(Br)\gamma$. The study confirms the existence of an accretion disk around the star and reveal the presence of an atmospherical envelope, twice as broad as the disk, where the atomic transitions of the hydrogen occurs. At last, I analyze in a theoretical framework the methods that investigate the astrophysical parameters of a source observed with single mode interferometers, such as model fitting and image reconstruction techniques. I particularly emphasize the issues that restrain the capacity of AMBER to image circumstellar environment of young stars.
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Contributor : Eric Tatulli <>
Submitted on : Wednesday, January 5, 2005 - 4:49:50 PM
Last modification on : Friday, November 6, 2020 - 4:11:01 AM
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Eric Tatulli. Traitement du signal en interferometrie monomode dans le cadre du projet AMBER. Application a l'observation interferometrique de l'environnement > circumstellaire des etoiles jeunes. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2004. Français. ⟨tel-00007927⟩

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